A flash mob, but with naked people. People synchronize their activity and all show up at a location (creating a flash mob), but they are all naked.

Every year on July 1st at 7PM an annual flesh mob takes place where hordes of naked people ascend on San Francisco Union Square, clap and shout for one minute and then disperse running away through the streets past high end fashion stores like gucci, macy's, and louis vuitton.